The skin, the largest organ of the human body, is the first barrier against physical, chemical and biological stress, thus providing the first protection against harmful environmental agents while preventing dehydration.
The skin barrier is a very complex system consisting of a large number of closely interrelated components. Changing any of these components results in an alteration of the barrier function culminating in skin alterations and diseases.
Recent studies have shown that the damage to the skin barrier is at the center of the onset of diseases, being still in discussion whether it is a primary cause or a secondary effect: opposing hypothesis see, on the one hand, skin alterations as triggers of the inflammation, on the other hand, damage to the barrier as an effect of the inflammatory response to allergens or irritants.
The alteration of the barrier and of immunological mechanisms can play an important role in promoting and supporting skin lesions and inflammation. Skin inflammation is associated with an abnormal acute or chronic condition. The skin inflammatory response involves a series of complex interactions between cellular mediators, i.e. keratinocytes, mast cells and macrophages, and molecular mediators such as cytokines and chemokines.
It is known that an uncontrolled release of reactive oxygen species (ROS) is involved in aging and in various skin pathologies. In fact, there are many agents able to produce an oxidative stress condition to the skin, including UV, pollutant, contaminant, additive and food preservative exposure, as well as side effects of some drugs.
The presence of free radicals and moisture loss are the main causes of skin alterations, in particular of skin aging.
Hyaluronic acid is a primary component of glycosaminoglycans, intercellular key substances responsible for skin hydration. Because of its physical and chemical properties, in fact, it is able to absorb and retain large amounts of water. Over time, the content of hyaluronic acid in the skin tends to decrease with a progressive decrease in the level of hydration, turgescence and tissue plasticity.
In addition to its moisturizing function, hyaluronic acid is a molecule essential for the formation of the collagen matrix and elastic fibers and plays an important role in preventing cell and tissue damage from physical stress. Recently, its involvement in the contact sensitization process, such as in ACD, allergic contact dermatitis, has also been highlighted.
Skin inflammation mediated by the innate immune system is a crucial step in the sensitization to contact allergens. The study of Philipp R. Esser et al., Contact Sensitizers Induce Skin Inflammation via ROS Production and Hyaluronic Acid Degradation, PLoS ONE, www.plosone.org Jul. 1, 2012, Volume 7, Issue 7, e41340, shows that the application of sensitizing agents leads to a degradation of hyaluronic acid, whose fragments trigger the inflammatory process. ROS are involved in this process because the degradation of hyaluronic acid is ROS-dependent.
The object of the present invention is to provide an efficient means of prevention and treatment of alterations and disorders of the skin, such as sensitization, aging, oxidative stress, inflammation, skin diseases in general and, in particular, of inflammatory origin, a means having also an action of skin barrier recovery and in particular of reactivation of the natural hydration capacity of the connective tissues. According to such an object, it is desired to at least safeguard, if not improve, the integrity and functionality of the skin barrier and homeostasis.